Apparatuses and methods for performing logical operations using sensing circuitry

ABSTRACT

The present disclosure includes apparatuses and methods related to performing logical operations using sensing circuitry. An example apparatus comprises an array of memory cells and sensing circuitry coupled to the array. The sensing circuitry is configured to perform a logical operation using a data value stored in a first memory cell coupled to a sense line as a first input and a data value stored in a second memory cell coupled to the sense line as a second input. The sensing circuitry is configured to perform the logical operation without transferring data via a sense line address access.

PRIORITY INFORMATION

This application is a Continuation of U.S. application Ser. No.16/215,026, filed Dec. 10, 2018, which issues as U.S. Pat. No.10,431,264 on Oct. 1, 2019, which is a Continuation of U.S. applicationSer. No. 15/965,733, filed Apr. 27, 2018, which issued as U.S. Pat. No.10,153,009 on Dec. 11, 2018, which is a Continuation of U.S. applicationSer. No. 15/688,545, filed Aug. 28, 2017, which issues as U.S. Pat. No.9,959,913 on May 1, 2018, which is a Continuation of U.S. applicationSer. No. 15/270,761, filed Sep. 20, 2016, which issued as U.S. Pat. No.9,892,766 on Feb. 13, 2018, which is a Continuation of U.S. applicationSer. No. 14/878,452, filed Oct. 8, 2015, which issued as U.S. Pat. No.9,472,265 on Oct. 18, 2016, which is a Continuation of U.S. applicationSer. No. 13/784,219, filed Mar. 4, 2013, which issued as U.S. Pat. No.9,158,667 on Oct. 13, 2015, the contents of which are included herein byreference.

TECHNICAL FIELD

The present disclosure relates generally to semiconductor memory andmethods, and more particularly, to apparatuses and methods related toperforming logical operations using sensing circuitry.

BACKGROUND

Memory devices are typically provided as internal, semiconductor,integrated circuits in computers or other electronic systems. There aremany different types of memory including volatile and non-volatilememory. Volatile memory can require power to maintain its data (e.g.,host data, error data, etc.) and includes random access memory (RAM),dynamic random access memory (DRAM), static random access memory (SRAM),synchronous dynamic random access memory (SDRAM), and thyristor randomaccess memory (TRAM), among others. Non-volatile memory can providepersistent data by retaining stored data when not powered and caninclude NAND flash memory, NOR flash memory, and resistance variablememory such as phase change random access memory (PCRAM), resistiverandom access memory (RRAM), and magnetoresistive random access memory(MRAM), such as spin torque transfer random access memory (STT RAM),among others.

Electronic systems often include a number of processing resources (e.g.,one or more processors), which may retrieve and execute instructions andstore the results of the executed instructions to a suitable location. Aprocessor can comprise a number of functional units such as arithmeticlogic unit (ALU) circuitry, floating point unit (FPU) circuitry, and/ora combinatorial logic block, for example, which can be used to executeinstructions by performing logical operations such as AND, OR, NOT,NAND, NOR, and XOR logical operations on data (e.g., one or moreoperands). For example, the functional unit circuitry (FUC) may be usedto perform arithmetic operations such as addition, subtraction,multiplication, and/or division on operands.

A number of components in an electronic system may be involved inproviding instructions to the FUC for execution. The instructions may begenerated, for instance, by a processing resource such as a controllerand/or host processor. Data (e.g., the operands on which theinstructions will be executed) may be stored in a memory array that isaccessible by the FUC. The instructions and/or data may be retrievedfrom the memory array and sequenced and/or buffered before the FUCbegins to execute instructions on the data. Furthermore, as differenttypes of operations may be executed in one or multiple clock cyclesthrough the FUC, intermediate results of the instructions and/or datamay also be sequenced and/or buffered.

In many instances, the processing resources (e.g., processor and/orassociated FUC) may be external to the memory array, and data isaccessed via a bus between the processing resources and the memory arrayto execute a set of instructions. Processing performance may be improvedin a processor-in-memory (PIM) device, in which a processor may beimplemented internal and/or near to a memory (e.g., directly on a samechip as the memory array), which may conserve time and power inprocessing. However, such PIM devices may have various drawbacks such asan increased chip size. Moreover, such PIM devices may still consumeundesirable amounts of power in association with performing logicaloperations (e.g., compute functions).

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an apparatus in the form of a computingsystem including a memory system in accordance with a number ofembodiments of the present disclosure.

FIG. 2A illustrates a schematic diagram of a portion of a memory arraycoupled to sensing circuitry in accordance with a number of embodimentsof the present disclosure.

FIG. 2B illustrates a timing diagram associated with performing alogical operation using sensing circuitry in accordance with a number ofembodiments of the present disclosure.

FIG. 3 illustrates a schematic diagram of a portion of sensing circuitryin accordance with a number of embodiments of the present disclosure.

DETAILED DESCRIPTION

The present disclosure includes apparatuses and methods related toperforming logical operations using sensing circuitry. An exampleapparatus comprises an array of memory cells and sensing circuitrycoupled to the array. The sensing circuitry is configured to perform alogical operation using a data value stored in a first memory cellcoupled to a sense line as a first input and a data value stored in asecond memory cell coupled to the sense line as a second input. Thesensing circuitry is configured to perform the logical operation withouttransferring data via a sense line address access.

A number of embodiments of the present disclosure can provide improvedparallelism and/or reduced power consumption in association withperforming compute functions as compared to previous systems such asprevious PIM systems and systems having an external processor (e.g., aprocessing resource located external from a memory array, such as on aseparate integrated circuit chip). For instance, a number of embodimentscan provide for performing fully complete compute functions such asinteger add, subtract, multiply, divide, and CAM (content addressablememory) functions without transferring data out of the memory array andsensing circuitry via a bus (e.g., data bus, address bus, control bus),for instance. Such compute functions can involve performing a number oflogical operations (e.g., AND, NOT, NOR, NAND, XOR, etc.). However,embodiments are not limited to these examples. For instance, performinglogical operations can include performing a number of non-boolean logicoperations such as copy, compare, destroy, etc.

In previous approaches, data may be transferred from the array andsensing circuitry (e.g., via a bus comprising input/output (I/O) lines)to a processing resource such as a processor, microprocessor, and/orcompute engine, which may comprise ALU circuitry and/or other functionalunit circuitry configured to perform the appropriate logical operations.However, transferring data from a memory array and sensing circuitry tosuch processing resource(s) can involve significant power consumption.Even if the processing resource is located on a same chip as the memoryarray, significant power can be consumed in moving data out of the arrayto the compute circuitry, which can involve performing a sense lineaddress access (e.g., firing of a column decode signal) in order totransfer data from sense lines onto I/O lines, moving the data to thearray periphery, and providing the data to the compute function.

Furthermore, the circuitry of the processing resource(s) (e.g., computeengine) may not conform to pitch rules associated with a memory array.For example, the cells of a memory array may have a 4F² or 6F² cellsize, where “F” is a feature size corresponding to the cells. As such,the devices (e.g., logic gates) associated with ALU circuitry ofprevious PIM systems may not be capable of being formed on pitch withthe memory cells, which can affect chip size and/or memory density, forexample.

In the following detailed description of the present disclosure,reference is made to the accompanying drawings that form a part hereof,and in which is shown by way of illustration how one or more embodimentsof the disclosure may be practiced. These embodiments are described insufficient detail to enable those of ordinary skill in the art topractice the embodiments of this disclosure, and it is to be understoodthat other embodiments may be utilized and that process, electrical,and/or structural changes may be made without departing from the scopeof the present disclosure. As used herein, the designator “N,”particularly with respect to reference numerals in the drawings,indicates that a number of the particular feature so designated can beincluded. As used herein, “a number of” a particular thing can refer toone or more of such things (e.g., a number of memory arrays can refer toone or more memory arrays).

The figures herein follow a numbering convention in which the firstdigit or digits correspond to the drawing figure number and theremaining digits identify an element or component in the drawing.Similar elements or components between different figures may beidentified by the use of similar digits. For example, 130 may referenceelement “30” in FIG. 1, and a similar element may be referenced as 230in FIG. 2. As will be appreciated, elements shown in the variousembodiments herein can be added, exchanged, and/or eliminated so as toprovide a number of additional embodiments of the present disclosure. Inaddition, as will be appreciated, the proportion and the relative scaleof the elements provided in the figures are intended to illustratecertain embodiments of the present invention, and should not be taken ina limiting sense.

FIG. 1 is a block diagram of an apparatus in the form of a computingsystem 100 including a memory device 120 in accordance with a number ofembodiments of the present disclosure. As used herein, a memory device120, a memory array 130, and/or sensing circuitry 150 might also beseparately considered an “apparatus.”

System 100 includes a host 110 coupled to memory device 120, whichincludes a memory array 130. Host 110 can be a host system such as apersonal laptop computer, a desktop computer, a digital camera, a mobiletelephone, or a memory card reader, among various other types of hosts.Host 102 can include a system motherboard and/or backplane and caninclude a number of processing resources (e.g., one or more processors,microprocessors, or some other type of controlling circuitry). Thesystem 100 can include separate integrated circuits or both the host 110and the memory device 120 can be on the same integrated circuit. Thesystem 100 can be, for instance, a server system and/or a highperformance computing (HPC) system and/or a portion thereof. Althoughthe example shown in FIG. 1 illustrates a system having a Von Neumannarchitecture, embodiments of the present disclosure can be implementedin non-Von Neumann architectures (e.g., a Turing machine), which may notinclude one or more components (e.g., CPU, ALU, etc.) often associatedwith a Von Neumann architecture.

For clarity, the system 100 has been simplified to focus on featureswith particular relevance to the present disclosure. The memory array130 can be a DRAM array, SRAM array, STT RAM array, PCRAM array, TRAMarray, RRAM array, NAND flash array, and/or NOR flash array, forinstance. The array 130 can comprise memory cells arranged in rowscoupled by access lines (which may be referred to herein as word linesor select lines) and columns coupled by sense lines (which may bereferred to herein as digit lines or data lines). Although a singlearray 130 is shown in FIG. 1, embodiments are not so limited. Forinstance, memory device 120 may include a number of arrays 130 (e.g., anumber of banks of DRAM cells). An example DRAM array is described inassociation with FIG. 2.

The memory device 120 includes address circuitry 142 to latch addresssignals provided over an I/O bus 156 (e.g., a data bus) through I/Ocircuitry 144. Address signals are received and decoded by a row decoder146 and a column decoder 152 to access the memory array 130. Data can beread from memory array 130 by sensing voltage and/or current changes onthe sense lines using sensing circuitry 150. The sensing circuitry 150can read and latch a page (e.g., row) of data from the memory array 130.The I/O circuitry 144 can be used for bi-directional data communicationwith host 110 over the I/O bus 156. The write circuitry 148 is used towrite data to the memory array 130.

Control circuitry 140 decodes signals provided by control bus 154 fromthe host 110. These signals can include chip enable signals, writeenable signals, and address latch signals that are used to controloperations performed on the memory array 130, including data read, datawrite, and data erase operations. In various embodiments, the controlcircuitry 140 is responsible for executing instructions from the host110. The control circuitry 140 can be a state machine, a sequencer, orsome other type of controller.

An example of the sensing circuitry 150 is described further below inassociation with FIGS. 2 and 3. For instance, in a number ofembodiments, the sensing circuitry 150 can comprise a number of senseamplifiers (e.g., sense amplifier 206 shown in FIG. 2 or sense amplifier306 shown in FIG. 3) and a number of compute components, which maycomprise an accumulator (e.g., compute component 231 shown in FIG. 2)and can be used to perform logical operations (e.g., on data associatedwith complementary sense lines). In a number of embodiments, the sensingcircuitry (e.g., 150) can be used to perform logical operations usingdata stored in array 130 as inputs and store the results of the logicaloperations back to the array 130 without transferring via a sense lineaddress access (e.g., without firing a column decode signal). As such,various compute functions can be performed within using sensingcircuitry 150 rather than being performed by processing resourcesexternal to the sensing circuitry (e.g., by a processor associated withhost 110 and/or other processing circuitry, such as ALU circuitry,located on device 120 (e.g., on control circuitry 140 or elsewhere)). Invarious previous approaches, data associated with an operand, forinstance, would be read from memory via sensing circuitry and providedto external ALU circuitry via local I/O lines. The external ALUcircuitry would perform compute functions using the operands and theresult would be transferred back to the array via the local I/O lines.In contrast, in a number of embodiments of the present disclosure,sensing circuitry (e.g., 150) is configured to perform logicaloperations on data stored in memory (e.g., array 130) and store theresult to the memory without enabling a local I/O line coupled to thesensing circuitry.

As such, in a number of embodiments, circuitry external to array 130 andsensing circuitry 150 is not needed to perform compute functions as thesensing circuitry 150 can perform the appropriate logical operations toperform such compute functions without the use of an external processingresource. Therefore, the sensing circuitry 150 may be used complimentand/or to replace, at least to some extent, such an external processingresource (or at least the bandwidth of such an external processingresource). However, in a number of embodiments, the sensing circuitry150 may be used to perform logical operations (e.g., to executeinstructions) in addition to logical operations performed by an externalprocessing resource (e.g., host 110). For instance, host 110 and/orsensing circuitry 150 may be limited to performing only certain logicaloperations and/or a certain number of logical operations.

FIG. 2 illustrates a schematic diagram of a portion of a memory array230 coupled to sensing circuitry in accordance with a number ofembodiments of the present disclosure. In this example, the memory array230 is a DRAM array of 1T1C (one transistor one capacitor) memory cellseach comprised of an access device 202 (e.g., transistor) and a storageelement 203 (e.g., a capacitor). In a number of embodiments, the memorycells are destructive read memory cells (e.g., reading the data storedin the cell destroys the data such that the data originally stored inthe cell is refreshed after being read). The cells of array 230 arearranged in rows coupled by word lines 204-0 (Row0), 204-1 (Row1),204-2, (Row2) 204-3 (Row3), . . . , 204-N (RowN) and columns coupled bysense lines (e.g., digit lines) 205-1 (D) and 205-2 (D_). In thisexample, each column of cells is associated with a pair of complementarysense lines 205-1 (D) and 205-2 (D_). Although only a single column ofmemory cells is illustrated in FIG. 2A, embodiments are not so limited.For instance, a particular array may have a number of columns of memorycells and/or sense lines (e.g., 4,096, 8,192, 16,384, etc.). A gate of aparticular memory cell transistor 202 is coupled to its correspondingword line 204-0, 204-1, 204-2, 204-3, . . . , 204-N, a firstsource/drain region is coupled to its corresponding sense line 205-1,and a second source/drain region of a particular memory cell transistoris coupled to its corresponding capacitor 203. Although not illustratedin FIG. 2A, the sense line 205-2 may also be coupled to a column ofmemory cells.

The array 230 is coupled to sensing circuitry in accordance with anumber of embodiments of the present disclosure. In this example, thesensing circuitry comprises a sense amplifier 206 and a computecomponent 231. The sensing circuitry can be sensing circuitry 150 shownin FIG. 1. The sense amplifier 206 is coupled to the complementary senselines D, D_ corresponding to a particular column of memory cells. Thesense amplifier 206 can be a sense amplifier such as sense amplifier 306described below in association with FIG. 3. As such, the sense amp 206can be operated to determine a state (e.g., logic data value) stored ina selected cell. Embodiments are not limited to the example senseamplifier 206. For instance, sensing circuitry in accordance with anumber of embodiments described herein can include current-mode senseamplifiers and/or single-ended sense amplifiers (e.g., sense amplifierscoupled to one sense line).

In a number of embodiments, a compute component (e.g., 231) can comprisea number of transistors formed on pitch with the transistors of thesense amp (e.g., 206) and/or the memory cells of the array (e.g., 230),which may conform to a particular feature size (e.g., 4F², 6F², etc.).As described further below, the compute component 231 can, inconjunction with the sense amp 206, operate to perform various logicaloperations using data from array 230 as input and store the result backto the array 230 without transferring the data via a sense line addressaccess (e.g., without firing a column decode signal such that data istransferred to circuitry external from the array and sensing circuitryvia local I/O lines). As such, a number of embodiments of the presentdisclosure can enable performing logical operations and computingfunctions associated therewith using less power than various previousapproaches. Additionally, since a number of embodiments eliminate theneed to transfer data across local I/O lines in order to perform computefunctions, a number of embodiments can enable an increased parallelprocessing capability as compared to previous approaches.

In the example illustrated in FIG. 2, the circuitry corresponding tocompute component 231 comprises five transistors coupled to each of thesense lines D and D_; however, embodiments are not limited to thisexample. Transistors 207-1 and 207-2 have a first source/drain regioncoupled to sense lines D and D_, respectively, and a second source/drainregion coupled to a cross coupled latch (e.g., coupled to gates of apair of cross coupled transistors, such as cross coupled NMOStransistors 208-1 and 208-2 and cross coupled PMOS transistors 209-1 and209-2. As described further herein, the cross coupled latch comprisingtransistors 208-1, 208-2, 209-1, and 209-2 can be referred to as asecondary latch (the cross coupled latch corresponding to sense amp 206can be referred to herein as a primary latch).

The transistors 207-1 and 207-2 can be referred to as pass transistors,which can be enabled via respective signals 211-1 (Passd) and 211-2(Passdb) in order to pass the voltages or currents on the respectivesense lines D and D_ to the inputs of the cross coupled latch comprisingtransistors 208-1, 208-2, 209-1, and 209-2 (e.g., the input of thesecondary latch). In this example, the second source/drain region oftransistor 207-1 is coupled to a first source/drain region oftransistors 208-1 and 209-1 as well as to the gates of transistors 208-2and 209-2. Similarly, the second source/drain region of transistor 207-2is coupled to a first source/drain region of transistors 208-2 and 209-2as well as to the gates of transistors 208-1 and 209-1.

A second source/drain region of transistor 208-1 and 208-2 is commonlycoupled to a negative control signal 212-1 (Accumb). A secondsource/drain region of transistors 209-1 and 209-2 is commonly coupledto a positive control signal 212-2 (Accum). The Accum signal 212-2 canbe a supply voltage (e.g., Vcc) and the Accumb signal can be a referencevoltage (e.g., ground). Enabling signals 212-1 and 212-2 activates thecross coupled latch comprising transistors 208-1, 208-2, 209-1, and209-2 corresponding to the secondary latch. The activated sense amp pairoperates to amplify a differential voltage between common node 217-1 andcommon node 217-2 such that node 217-1 is driven to one of the Accumsignal voltage and the Accumb signal voltage (e.g., to one of Vcc andground), and node 217-2 is driven to the other of the Accum signalvoltage and the Accumb signal voltage. As described further below, thesignals 212-1 and 212-2 are labeled “Accum” and “Accumb” because thesecondary latch can serve as an accumulator while being used to performa logical operation. In a number of embodiments, an accumulatorcomprises the cross coupled transistors 208-1, 208-2, 209-1, and 209-2forming the secondary latch as well as the pass transistors 207-1 and208-2. As described further herein, in a number of embodiments, acompute component comprising an accumulator coupled to a sense amplifiercan be configured to perform a logical operation that comprisesperforming an accumulate operation on a data value represented by asignal (e.g., voltage or current) on at least one of a pair ofcomplementary sense lines.

The compute component 231 also includes inverting transistors 214-1 and214-2 having a first source/drain region coupled to the respective digitlines D and D_. A second source/drain region of the transistors 214-1and 214-2 is coupled to a first source/drain region of transistors 216-1and 216-2, respectively. The gates of transistors 214-1 and 214-2 arecoupled to a signal 213 (InvD). The gate of transistor 216-1 is coupledto the common node 217-1 to which the gate of transistor 208-2, the gateof transistor 209-2, and the first source/drain region of transistor208-1 are also coupled. In a complementary fashion, the gate oftransistor 216-2 is coupled to the common node 217-2 to which the gateof transistor 208-1, the gate of transistor 209-1, and the firstsource/drain region of transistor 208-2 are also coupled. As such,enabling signal InvD serves to invert the data value stored in thesecondary latch and drives the inverted value onto sense lines 205-1 and205-2.

In FIG. 2, the compute component 231 is configured to perform an AND,NAND, and/or a NOT (e.g., invert) operation. The following example willdemonstrate how a 3-input NAND operation can be performed using datastored in array 230 as the inputs, and how the result of the NANDoperation can be stored in the array via operation of the sensingcircuitry (e.g., sense amp 206 and compute component 231). The exampleinvolves using the data values (e.g., logic 1 or logic 0) stored in thememory cells coupled to word lines 204-0, 204-1, and 204-2 and commonlycoupled to sense line 205-1 as the respective inputs of a NANDoperation. The result of the NAND operation will be stored in the memorycell coupled to word line 204-3 and to sense line 205-1 (e.g., byoverwriting the previous data value stored in the cell).

A first operation phase of the 3-input NAND operation includesperforming a sensing operation on the Row0 memory cell using sense amp206 to determine its stored data value, which serves as a first input ofthe NAND operation. The sense amp 206 can operate in a similar manner assense amp 306 described below in association with FIG. 3. The sensingoperation involves enabling Row0 (e.g., to activate the accesstransistor 202) and results in a voltage (e.g., Vcc) corresponding to alogic 1 or a voltage (e.g., ground) corresponding to a logic 0 being onsense line D (and the other voltage being on complementary sense lineD_), such that the sensed data value is stored in the primary latchcorresponding to sense amp 206. After the Row0 memory cell is sensed,the Passd and Passdb signals 211-1/211-2 are enabled and the Accumb andAccum signals 212-1/212-2 are enabled, which results in the sensed datavalue stored in the Row0 memory cell being copied to the secondary latchcorresponding to compute component 231. The Passd and Passdb signals arethen disabled; however, the Accum and Accumb signals remain enabled(during the second, third, and fourth operation phase as describedbelow). Row0 is then disabled and equilibration occurs. As describedbelow in association with FIG. 3, equilibration can involve shorting thecomplementary sense lines D and D_ together at an equilibration voltage,which can be Vcc/2, for instance. Equilibration can occur, for instance,prior to a memory cell sensing operation.

A second phase of the 3-input NAND operation includes performing asensing operation on the Row1 memory cell using sense amp 206 todetermine its stored data value, which serves as a second input of theNAND operation. As such, Row1 is enabled and the sense lines D and D areeach driven to a different one of Vcc and ground. In this example, a Vccvoltage on sense line D corresponds to a logic 1 stored in a memory celland a ground voltage on sense line D corresponds to a logic 0; however,embodiments are not limited to this example. After the Row1 memory cellis sensed, the Passd signal 211-1 is enabled while the Passdb signal211-2 remains disabled (e.g., only Passd is enabled). Recall that theAccumb and Accum signals 212-1/212-2 remain enabled. If the data valuestored in the Row1 memory cell is a logic 0, then the accumulated valueassociated with the secondary latch is asserted low such that thesecondary latch stores logic 0. If the data value stored in the Row1memory cell is not a logic 0, then the secondary latch retains itsstored Row0 data value (e.g., a logic 1 or a logic 0). As such, in thisexample, the secondary latch is serving as a zeroes (0s) accumulator.The Passd signal is then disabled, Row1 is disabled, and equilibrationoccurs.

A third phase of the 3-input NAND operation includes performing asensing operation on the Row2 memory cell using sense amp 206 todetermine its stored data value, which serves as a third input of theNAND operation. As such, Row2 is enabled and the sense lines D and D areeach driven to a different one of Vcc and ground. After the Row2 memorycell is sensed, the Passd signal 211-1 is enabled while the Passdbsignal 211-2 remains disabled (e.g., only Passd is enabled). Recall thatthe Accumb and Accum signals 212-1/212-2 remain enabled. If the datavalue stored in the Row2 memory cell is a logic 0, then the accumulatedvalue associated with the secondary latch is asserted low such that thesecondary latch stores logic 0. If the data value stored in the Row2memory cell is not a logic 0, then the secondary latch retains itspreviously stored value (e.g., its stored value). As such, the valuestored in the secondary latch (e.g., the output of the accumulator) isthe AND of the data values stored in the respective Row0, Row1, and Row2memory cells. The Passd signal is then disabled, Row2 is disabled, andequilibration occurs.

The fourth phase of the 3-input NAND operation includes disablingequilibration such that sense lines D and D_ are floating. The InvDsignal 213 is then enabled, which results in an inverting of the datavalue stored the secondary latch (e.g., inverting the accumulatedoutput). As such, if any of the memory cells of Row0 to Row2 stored alogic 0 (e.g., if any of the three inputs of the NAND operation werelogic 0), then the sense line D_ will carry a voltage corresponding tologic 0 (e.g., ground voltage) and sense line D will carry a voltagecorresponding to logic 1 (e.g., Vcc). If all of the memory cells of Row0to Row2 stored a logic 1 (e.g., all of the three inputs of the NANDoperation were logic 1), then the sense line D_ will carry a voltagecorresponding to logic 1 and sense line D will carry a voltagecorresponding to logic 0. The primary latch of sense amp 206 is thenenabled and the sense line D now contains the NANDed result of therespective input data values from the Row0 to Row2 memory cells. Assuch, sense line D will be at Vcc if any of the Row0 to Row 2 memorycells stored a logic 0 and sense line D will be at ground if all of theRow0 to Row2 memory cells stored a logic 1. The result of the NANDoperation is then stored back to a memory cell of array 230. In thisexample, the result of the NAND operation can be stored to the Row3memory cell. Storing the result of the NAND operation to the Row3 memorycell simply involves activating the Row3 access transistor 202 byenabling Row3. The capacitor 203 of the Row3 memory cell will be drivento a voltage corresponding to the data value on the sense line D (e.g.,logic 1 or logic 0), which essentially overwrites whatever data valuewas previously stored in the Row3 memory cell. Embodiments are not solimited. For instance, in a number of embodiments, the result of thelogical operation may be written to a memory cell other than a memorycell of Row3. For example, the result can be stored back to one of thememory cells that initially stored the data used as inputs of theoperation (e.g., to one of cells of Row0, Row1, and Row2). In a numberof embodiments, the result of the logical operation may not be storedback to the array. For instance, after performing the logical operation,the result may be transferred from an accumulator (e.g., the accumulatorof compute component 231) to an external device (e.g., via local I/Olines coupled to the sense amp).

Although the above example involved a 3-input NAND operation,embodiments are not so limited. For instance, in a number ofembodiments, the number of inputs can be equal to the number of rows(e.g., N) associated with a particular array. That is, the same sensingcircuitry described in FIG. 2 can be used to perform an N-input NANDfunction. Sensing circuitry such as that described in FIG. 2 can alsoenable performance of numerous logical operations in parallel. Forinstance, in an array may having 16K columns, 16K logical operations canbe performed in parallel, without transferring data from the array andsensing circuitry via a bus and/or without transferring data from thearray and sensing circuitry via local I/O lines.

Also, one of ordinary skill in the art will appreciate that the abilityto perform NAND logical operations can enable performance of morecomplex computing functions such as addition, subtraction, andmultiplication, among other primary math functions and/or patterncompare functions. For example, a series of NAND operations can becombined to perform a full adder function. As an example, if a fulladder requires 12 NAND gates to add two data values along with a carryin and carry out, a total of 384 NAND operations (12×32) could beperformed to add two 32 bit numbers. Embodiments of the presentdisclosure can also be used to perform logical operations that may benon-boolean (e.g., copy, compare, etc.) and/or may be more or lesscomplex than a NAND operation.

Additionally, in a number of embodiments, the inputs to a logicaloperation performed may not be data values stored in the memory array towhich the sensing circuitry (e.g., 150) is coupled. For instance, anumber of inputs to a logical operation can be sensed by a senseamplifier (e.g., 206) without activating a row of the array (e.g., 230).As an example, the number of inputs can be received by the sense amp 206via I/O lines coupled thereto (e.g., I/O lines 334-1 and 334-2 shown inFIG. 3). Such inputs may be provided to the sense amp 206 (e.g., via theappropriate I/O lines) from a source external to the array 230 such asfrom a host processor (e.g., host 110) and/or external controller, forinstance. As another example, in association with performing a logicaloperation, the inputs to a particular sense amp (e.g., 206) and itscorresponding compute component (e.g., 231) may be received from adifferent sense amp/compute component pair. For instance, a data value(e.g., logical result) stored in a first accumulator coupled to a firstcolumn of cells may be transferred to a different (e.g., neighboring)sense amp/compute component pair associated with a different column ofcells, which may or may not be located in the same array as the firstcolumn.

Embodiments of the present disclosure are not limited to the particularsensing circuitry configuration illustrated in FIG. 2. For instance,different compute component circuitry can be used to perform logicaloperations in accordance with a number of embodiments described herein.Although not illustrated in FIG. 2, in a number of embodiments, controlcircuitry can be coupled to array 230, sense amp 206, and/or computecomponent 231. Such control circuitry may be implemented on a same chipas the array and sensing circuitry and/or on an external processingresource such as an external processor, for instance, and can controlenabling/disabling various signals corresponding to the array andsensing circuitry in order to perform logical operations as describedherein.

FIG. 2B illustrates a timing diagram 285 associated with performing alogical operation using sensing circuitry in accordance with a number ofembodiments of the present disclosure. As an example, timing diagram 285can illustrate a phase of a 3-input NAND operation such as thatdescribed above. The timing diagram 285 illustrates voltage signalsassociated with performing a first phase of a logical operation. Asdescribed further below, performing the logical operation phaseillustrated in FIG. 2B can involve consuming significantly less energy(e.g., about half) than previous processing approaches, which mayinvolve providing a full swing between voltage rails (e.g., between asupply voltage and ground) to perform a compute function.

In the example illustrated in FIG. 2B, the voltage rails correspondingto complementary logic values (e.g., “1” and “0”) are a supply voltage274 (VDD) and a ground voltage 272 (Gnd). Prior to performing a logicaloperation, equilibration can occur such that the complementary senselines D and D_ are shorted together at an equilibration voltage 225(VDD/2). Equilibration is described further below in association withFIG. 3.

At time t₁, the equilibration signal 226 is deactivated, and then a rowis activated (e.g., the row corresponding to a memory cell whose datavalue is to be sensed). Signal 204 represents the voltage signal appliedto the selected row. When row signal 204 reaches the threshold voltage(Vt) of the access transistor (e.g., 202) corresponding to the selectedcell, the access transistor turns on and couples the sense line D to theselected memory cell (e.g., to the capacitor 203 if the cell is a 1T1CDRAM cell), which creates a differential voltage signal between thesense lines D and D_ (e.g., as indicated by signals 205-1 and 205-2,respectively) between times t₂ and t₃. The voltage of the selected cellis represented by signal 203. Due to conservation of energy, creatingthe differential signal between D and D_ (e.g., by coupling the cell toD) does not consume energy, since the energy associated withactivating/deactivating the row signal 204 can be amortized over theplurality of memory cells coupled to the row.

At time t₃, the sense amp fires (e.g., the positive control signal 231(e.g., PSA 331 shown in FIG. 3) goes high, and the negative controlsignal 228 (e.g., RNL_ 328) goes low), which amplifies the differentialsignal. The primary energy consumption occurs in charging the sense lineD 205-1 from VDD/2 to VDD.

At time t₄, the pass transistor 207-1 and/or 207-2 is activated,depending on the particular logic operation. Since timing diagram 285 isdescribing a first phase of a NAND operation, both pass transistors207-1 and 207-2 are activated (as described above, in subsequent phasesof a NAND operation only one of the pass transistors (e.g., 207-1) isactivated during accumulate operations). At time t₅, the accumulatorcontrol signals 212-1 (Accumb) and 212-2 (Accum) are activated. Asdescribed above, in subsequent phases of a NAND operation, theaccumulator control signals 212-1 and 212-2 would already be activated.As such, in this example, activating the control signals 212-1 and 212-2activates the accumulator. If the accumulator was previously activated,then activating passd 211 results in accumulating the data valuecorresponding to the voltage signal 205-1.

At time t₆, the pass transistors 207-1 and 207-2 are deactivated;however, since the accumulator control signals 212-1 and 212-2 remainactivated, an accumulated result is stored (e.g., latched) in theaccumulator. At time t₇, the row signal 204 is deactivated, and thearray sense amps are deactivated at time t₈ (e.g., sense amp controlsignals 228 and 231 are deactivated).

At time t₉, the sense lines D and D_ are equilibrated (e.g.,equilibration signal 226 is activated), as illustrated by sense linevoltage signals 205-1 and 205-2 moving from their respective rail valuesto the equilibration voltage 225 (VDD/2). The equilibration consumeslittle energy due to the law of conservation of energy.

The example logic operation phase described in association with FIG. 2involves accumulating a data value (e.g., a data value sensed from amemory cell and/or a data value corresponding to a voltage or current ofa sense line). Due to conservation of energy, the energy consumed inperforming the logic operation phase is approximately equal to theenergy consumed during charging of the capacitance of the sense line Dor D_ from VDD/2 to VDD, which begins at time t₃ (e.g., when the senseamp is fired). As such, a logical operation is performed that consumesapproximately the energy used to charge a sense line (e.g., digit line)from VDD/2 to VDD. In contrast, various previous processing approachesconsume at least an amount of energy used to charge a sense line fromrail to rail (e.g., from ground to VDD.

FIG. 3 illustrates a schematic diagram of a portion of sensing circuitryin accordance with a number of embodiments of the present disclosure. Inthis example, the portion of sensing circuitry comprises a senseamplifier 306. In a number of embodiments, one sense amplifier 306(e.g., “sense amp”) is provided for each column of memory cells in anarray (e.g., array 130). The sense amp 306 can be sense amp of a DRAMarray, for instance. In this example, sense amp 306 is coupled to a pairof complementary sense lines 305-1 (“D”) and 305-2 (“D_”). As such, thesense amp 306 is coupled to all of the memory cells in a respectivecolumn through sense lines D and D_.

The sense amplifier 306 includes a pair of cross coupled n-channeltransistors (e.g., NMOS transistors) 327-1 and 327-2 having theirrespective sources coupled to a negative control signal 328 (RNL_) andtheir drains coupled to sense lines D and D_, respectively. The senseamplifier 306 also includes a pair of cross coupled p-channeltransistors (e.g., PMOS transistors) 329-1 and 329-2 having theirrespective sources coupled to a positive control signal 331 (PSA) andtheir drains coupled to sense lines D and D_, respectively.

The sense amp 306 includes a pair of isolation transistors 321-1 and321-2 coupled to sense lines D and D_, respectively. The isolationtransistors 321-1 and 321-2 are coupled to a control signal 322 (ISO)that, when enabled, activates (e.g., turns on) the transistors 321-1 and321-2 to connect the sense amp 306 to a column of memory cells. Althoughnot illustrated in FIG. 3, the sense amp 306 may be coupled to a firstand a second memory array and can include another pair of isolationtransistors coupled to a complementary control signal (e.g., ISO_),which is disabled when ISO is enabled such that the sense amp 306 isisolated from a first array when sense amp 306 is coupled to a secondarray, and vice versa.

The sense amp 306 also includes circuitry configured to equilibrate thesense lines D and D_. In this example, the equilibration circuitrycomprises a transistor 324 having a first source/drain region coupled toan equilibration voltage 325 (dvc2), which can be equal to Vcc/2, whereVcc is a supply voltage associated with the array. A second source/drainregion of transistor 324 is coupled to a common first source/drainregion of a pair of transistors 323-1 and 323-2. The second source drainregions of transistors 323-1 and 323-2 are coupled to sense lines D andD_, respectively. The gates of transistors 324, 323-1, and 323-2 arecoupled to control signal 326 (EQ). As such, enabling EQ activates thetransistors 324, 323-1, and 323-2, which effectively shorts sense line Dto sense line D_ such that the sense lines D and D_ are equilibrated toequilibration voltage dvc2.

The sense amp 306 also includes transistors 332-1 and 332-2 whose gatesare coupled to a signal 333 (COLDEC). Signal 333 may be referred to as acolumn decode signal or a column select signal. The sense lines D and D_are connected to respective local I/O lines 334-1 (10) and 334-2 (IO_)responsive to enabling signal 333 (e.g., to perform an operation such asa sense line access in association with a read operation). As such,signal 333 can be enabled to transfer a signal corresponding to thestate (e.g., a logic data value such as logic 0 or logic 1) of thememory cell being accessed out of the array on the I/O lines 334-1 and334-2.

In operation, when a memory cell is being sensed (e.g., read), thevoltage on one of the sense lines D, D_ will be slightly greater thanthe voltage on the other one of sense lines D, D_. The PSA signal isthen driven high and the RNL_ signal is driven low to enable the senseamplifier 306. The sense line D, D having the lower voltage will turn onone of the PMOS transistor 329-1, 329-2 to a greater extent than theother of PMOS transistor 329-1, 329-2, thereby driving high the senseline D, D_ having the higher voltage to a greater extent than the othersense line D, D_ is driven high. Similarly, the sense line D, D_ havingthe higher voltage will turn on one of the NMOS transistor 327-1, 327-2to a greater extent than the other of the NMOS transistor 327-1, 327-2,thereby driving low the sense line D, D_ having the lower voltage to agreater extent than the other sense line D, D_ is driven low. As aresult, after a short delay, the sense line D, D_ having the slightlygreater voltage is driven to the voltage of the PSA signal (which can bethe supply voltage Vcc), and the other sense line D, D_ is driven to thevoltage of the RNL_ signal (which can be a reference potential such as aground potential). Therefore, the cross coupled NMOS transistors 327-1,327-2 and PMOS transistors 329-1, 329-2 serve as a sense amp pair, whichamplify the differential voltage on the sense lines D and D and serve tolatch a data value sensed from the selected memory cell. As used herein,the cross coupled latch of sense amp 306 may be referred to as a primarylatch. In contrast, and as described above in connection with FIG. 2, across coupled latch associated with a compute component (e.g., computecomponent 231 shown in FIG. 2) may be referred to as a secondary latch.

CONCLUSION

The present disclosure includes apparatuses and methods related toperforming logical operations using sensing circuitry. An exampleapparatus comprises an array of memory cells and sensing circuitrycoupled to the array. The sensing circuitry is configured to perform alogical operation using a data value stored in a first memory cellcoupled to a sense line as a first input and a data value stored in asecond memory cell coupled to the sense line as a second input. Thesensing circuitry is configured to perform the logical operation withouttransferring data via a sense line address access.

Although specific embodiments have been illustrated and describedherein, those of ordinary skill in the art will appreciate that anarrangement calculated to achieve the same results can be substitutedfor the specific embodiments shown. This disclosure is intended to coveradaptations or variations of one or more embodiments of the presentdisclosure. It is to be understood that the above description has beenmade in an illustrative fashion, and not a restrictive one. Combinationof the above embodiments, and other embodiments not specificallydescribed herein will be apparent to those of skill in the art uponreviewing the above description. The scope of the one or moreembodiments of the present disclosure includes other applications inwhich the above structures and methods are used. Therefore, the scope ofone or more embodiments of the present disclosure should be determinedwith reference to the appended claims, along with the full range ofequivalents to which such claims are entitled.

In the foregoing Detailed Description, some features are groupedtogether in a single embodiment for the purpose of streamlining thedisclosure. This method of disclosure is not to be interpreted asreflecting an intention that the disclosed embodiments of the presentdisclosure have to use more features than are expressly recited in eachclaim. Rather, as the following claims reflect, inventive subject matterlies in less than all features of a single disclosed embodiment. Thus,the following claims are hereby incorporated into the DetailedDescription, with each claim standing on its own as a separateembodiment.

What is claimed is:
 1. A system, comprising: a host configured togenerate instructions; and a memory device comprising an array of memorycells coupled to sensing circuitry comprising a first latch and a secondlatch, wherein the memory device is configured to: receive aninstruction from the host; and execute the instruction to perform atleast one of a NAND operation or an AND operation using data valuesstored in the array as inputs by controlling the sensing circuitrywithout transferring the data values externally from the memory device.2. The system of claim 1, wherein the second latch serves as anaccumulator.
 3. The system of claim 2, wherein the second latch iscoupled to the first latch via a pair of pass transistors.
 4. The systemof claim 1, wherein the first latch is a latch is a sense amplifierlatch and the second latch is an accumulator latch.
 5. The system ofclaim 1, wherein the host comprises a processor and is coupled to thememory device via a bus.
 6. The system of claim 1, wherein the arraycomprises a plurality of columns of memory cells, and wherein executingthe instruction includes performing a respective plurality of the atleast one of the NAND operation or the AND operation in parallel.
 7. Thesystem of claim 1, wherein the system is a server system, and whereinthe memory device comprises a dynamic random access memory (DRAM)device.
 8. The system of claim 1, wherein the at least one of the NANDoperation or the AND operation is a first logical operation, and whereinthe memory device is configured to execute the instruction to performmultiple logical operations to perform a compute function selected fromthe group comprising: an addition operation; a subtraction operation;and a multiplication operation.
 9. The system of claim 1, wherein thesystem comprises an electronic system selected from the groupcomprising: a laptop computer; a desktop computer; a digital camera; anda mobile telephone.
 10. A method, comprising: providing an instructionto a memory device from a host, wherein the memory device comprises anarray of memory cells coupled to sensing circuitry comprising a firstlatch and a second latch; and executing, on the memory device, theinstruction to perform at least one of a NAND operation or an ANDoperation using data values stored in the array as inputs by controllingthe first latch and the second latch without transferring the datavalues externally from the memory device.
 11. The method of claim 10,wherein performing the at least one of the NAND operation and the ANDoperation comprises providing control signals to the sensing circuitryto perform the operation by using a first data value on a sense linecorresponding to a column of the array at a first point in time as afirst input and a second data value on the sense line at a second pointin time as a second input.
 12. The method of claim 11, furthercomprising providing the control signals to the sensing circuitry from acontroller local to the memory device.
 13. The method of claim 11,wherein performing the at least one of the NAND operation and the ANDoperation without transferring the data values externally from thememory device comprises performing the at least one of the NANDoperation or the AND operation without transferring the data valuesexternally from the array and the sensing circuitry.
 14. The method ofclaim 10, further comprising providing the instruction to the memorydevice from an external host processor.
 15. The method of claim 10,wherein the array comprises a plurality of columns each corresponding toa pair of complementary sense lines, wherein the sensing circuitrycomprises, for each respective one of the plurality of columns: a senseamplifier comprising the first latch; and a corresponding computecomponent comprising the second latch; and wherein the method furthercomprises controlling the sensing circuitry to perform a plurality ofthe at least one of the NAND operation or the AND operation in parallel,the plurality of logical operations being a same quantity as theplurality of columns.
 16. The method of claim 10, wherein performing theat least one of the NAND operation or the AND operation withouttransferring data externally from the memory device further comprisesperforming the at least one of the NAND operation or the AND operationwithout transferring data from the array and/or sensing circuitry viainput/output lines of the array.
 17. An apparatus, comprising: a senseamplifier comprising a first latch coupled to a pair of complementarysense lines of an array of memory cells; a second latch configured toserve as an accumulator and coupled to the sense amplifier via a pair ofpass transistors; and control circuitry configured to provide signals tothe first latch and the second latch in association with performing atleast one of a NAND operation or an AND operation using, as inputs, afirst data value latched by the first latch at a first point in time anda second data value represented by a signal on at least one of the pairof complementary sense lines at a second point in time.
 18. Theapparatus of claim 17, wherein the first data value is provided to thefirst latch without activating an access line of the array.
 19. Theapparatus of claim 17, wherein the apparatus is a system comprising: amemory device comprising: the array of memory cells; the sensingcircuitry; and the control circuitry; and a host coupled to the memorydevice; and wherein the first data value is provided to the first latchfrom the host.
 20. The apparatus of claim 17, wherein the first latchand the second latch comprise respective cross-coupled latches.